Q&A: Thank-you Note Timing?
How long can I reasonably wait to send thank-you notes for gifts?
You'll probably be very busy (and exhausted) in the weeks before and after baby arrives, and your family and friends are sure to understand. Still, it’s best to send out those thank-you notes asap. Try to send a thank-you for shower presents and other pre-baby gifts before the big day, if possible. (We know it’s tough, but it’ll be easier now than when you’re changing diapers and waking up at all hours.)
For the gifts that you receive after delivery (and the leftovers from beforehand), shoot for getting notes in the mail by the time baby is two months old. And, if you don’t make the deadline, don’t convince yourself that you’ve waited too long. The rule here is the same as with wedding gifts — it's never too late to show gratitude.